How Does ISO Work?

The New York Institute of Photography is one of the world’s largest photography schools and because we are, we often publish fun and useful photography tips on our photography blog. Please enjoy!

What if I told you there was a way to prevent underexposed images with just one button? You are in luck, as this feature already exists. It’s called the ISO, and it’s one of the most powerful yet least understood settings for many photography students. Whether you’re using a point & shoot or a DSLR, you can utilize this functionality right now.

Think of your camera as a light gathering sponge. The higher the ISO number, the more light it soaks in. At ISO 200 for example, the camera gathers twice as much light as ISO 100. Notice how the images get progressively brighter in the sample above. The shutter speed and aperture did not change, only the ISO.